Surface Mount Optoelectronic Component with Lens Having Protruding Structure

ABSTRACT

The invention relates to a surface mount optoelectronic component with a lens attachment, the method for precising the lens position and the method to manufacture the whole component.

This is a divisional of U.S. patent application Ser. No. 12/692,814,filed Jan. 25, 2010, which is a divisional of U.S. patent applicationSer. No. 11/512,370, filed Aug. 30, 2006, which is based upon and claimsthe benefit of priority under 35 U.S.C. §119 from Malaysian patentapplication No. PI 20054103 filed on Sep. 1, 2005, the contents of allof which are incorporated herein by reference.

1. FIELD OF INVENTION

The invention relates to a surface mount optoelectronic component with alens attachment, the method for precising the lens position and themethod to manufacture the whole component.

2. PRIOR ART

Similar component has been described by many prior arts. Waitl et. al.has described in U.S. Pat. No. 6,610,563 a surface mount component wherean optical device is placed onto a base body. According to the patent, abase component with a semiconductor chip mounted in a recess is filledwith a casting compound. An optical device is then placed on top of thebase component so whereby the optical device comes into contact with thecasting compound; before the casting compound is cured. The wholeassembly is then cured to achieve adhesion between the base componentand the optical device.

This approach has the disadvantages that precise location of the opticaldevice is difficult because the optical device may move in the time whenit is cured with the base component.

SUMMARY OF INVENTION

According to one aspect of the present invention, there is provided anoptoelectronic component assembly based on surface mount technologycomprising:

an electrically conductive material which is used to serve as a basecomponent for the assembly,

an opaque material which is used to provide a housing for the wholecomponent assembly;

a cavity designed within the electrically conductive material where atleast one optoelectronic chip is mounted within,

file cavity being filled with an encapsulation material so that opticalradiation may be transmitted or received via this material,

a lens structure which is attached to the housing and which is locatedby a groove on the housing and a protruding structure on the lens.

The opaque material used to provide the housing may be made fromplastic.

Multiple, instead of one, optoelectronic chips may be mounted within thecavity.

Electrical connection(s) between the optoelectronic chip(s) and the basecomponent for the assembly may be provided by a metallic wire.

The groove may be formed around the cavity and used to position the lensstructure onto the base component.

Another preferred embodiment of the invention is where the encapsulationmaterial is silicone material.

Preferably, the silicone material has a hardness (Type A) of less than85 after being cured and hardened.

Another preferred embodiment of the invention is where the lensstructure is made from silicone.

It is also one of the preferred embodiments of the invention forsilicone to be used as a bonding material between the lens structure andthe base component.

One of the more preferred embodiments of the invention is where theencapsulation material, the lens structure and the bonding materialbetween the lens structure and the base component are silicone material.

It is recommended that the base and groove have a rough surface textureto promote better adhesion of the lens structure to the base component.

According to another aspect of the present invention, there is alsoprovided a method for producing a surface mount optoelectronic componentassembly, said method comprising the steps:

preparing the base component with one or more optoelectronic chip(s)mounted within the cavity,

filling the cavity with an encapsulation material,

curing the base component to harden the encapsulation material,

applying an amount of the same encapsulation material on the top of thebase component;

placing the lens structure on top and located by the groove,

then curing the the whole assembly to bond the lens and base componenttogether.

In the aforesaid method, heat may be used to cure the final assembly sothat the lens is bonded to the base component.

In the method, silicone may be used as the bonding material between thelens and the base component.

According to yet another aspect of the present invention, there isprovided a method for producing a lens structure for a surface mountoptoelectronic assembly using silicone as a base material, comprisingthe steps:

mold tool is fabricated with the required lens profile,

liquid silicone is dispensed into the tool,

the tool is heated so that the silicone is cured and hardened to formthe lens structure before being removed from the tool.

In any of the embodiments of the method of producing the surface mountoptoelectronic component assembly of the present invention, theencapsulation material used may be silicone.

The lens structure used in the method may also be made from silicone.

The optoelectronic component assembly of the present invention is alsodesigned to be more robust when used in the environment especially whenexposed to UV (ultraviolet) radiation.

For a better understanding of the invention and to show how it can becarried out into effect, some preferred embodiments thereof will now bedescribed by way of non-limiting examples, and where necessary withreference to the accompanying drawings.

3. BRIEF DESCRIPTION OF DRAWINGS

The drawings enclosed are as follows:

FIG. 1 is a top view of the base component of an optoelectroniccomponent assembly.

FIG. 2A is a cross sectional view of the base component shown in FIG. 1.

FIG. 2B is a blown up view of a portion of the base component generallycorresponding with the portion labeled 2B in FIG. 2A, and includes anenlarged view of the locating groove.

FIG. 3 is a cross sectional view of the invention after the lens isattached.

4. DETAILED DESCRIPTION OF SOME PREFERRED EMBODIMENTS

In an embodiment of the present invention, the optoelectronic componentbased on the surface mount technology is made up of a thick electricallyconductive material which is used to serve as the base for the assembly,an opaque plastic material which is used to provide the housing for thewhole component and a cavity designed within the plastic material wherean optoelectronic chip is mounted within. Multiple chips may also bemounted if required. This cavity is filled with a encapsulation materialso that optical radiation may be transmitted or received via thismaterial. Electrical connection(s) between the chip/chips and the basematerial is provided by a metallic wire.

The housing of the base component is designed in such a way whereby agroove is formed around the cavity. This groove is used to position thelens which is attached onto the base component. On the lens itself, aprotruding structure is made to locate into the groove found on the basecomponent. The arrangement ensures a precise fitting of the len withreference to the base component.

In an embodiment, the steps for the manufacture of the componentcomprise of the following. The base component is assembled with theoptoelectronic chip and electrical connections are made. The cavity thenfilled with the encapsulation material so that the whole cavity iscompletely filled. The base component is then cured to that theencapsulation material is hardened.

In an embodiment, the same encapsulation material is dispensed onto thetop of the base component. Following that, the lens is placed on topsuch that the encapsulation material forms a layer in between the lensand the base component. Sufficient encapsulation material is necessaryto ensure that the encapsulation material spreads all over the top ofthe base component till the extend that it flows into the groove andfills the groove. The component is then cured by heat so that the layerin between hardens and bonds the lens onto the base component. Thebonding is superior compared to prior arts due to the larger surfacearea provided by the groove. In addition, the rough surface texture ofthe base component further promotes adhesion.

In an embodiment, the preferred encapsulation system is based onsilicone. Liquid silicone is dispensed into the cavity of the basecomponent and is cured with heat. The same silicone material is used tomake the lens structure. Mold tools are fabricated with the requiredlens profile and liquid silicone is dispersed into the tools and curedwith heat so that it hardens before being removed front the tools. Thesame silicone material is also used for the bonding purpose. This commonmaterial used to fill the cavity, make the lens and also for bondingensures a good match in terms of thermal coefficient of expansion (CTE).The ensures that the adhesion between the parts is reliable and is notprone to cracks along the bonding interface due to CTE mismatch.

The silicone material also ensures robust reliability when the componentis exposed to the UV (ultraviolet) exposure in the environment comparedto epoxy resins which are described by the prior arts. In addition, thepreferred silicone material have a hardness (Type A) of less than 85after being cured and hardened. This soft characteristic of the siliconematerial ensures minimum mechanical stress to the optoelectronic chipmounted within. Consequently, the component demonstrates more superiorlifetime performance compared to prior arts employing epoxy resinsystems.

FIGS. 1-3 show a preferred embodiment of the present invention. Theinvention includes a base component made up of a thick electricallyconductive material (1) which is used to serve as the base for theassembly, an opaque plastic material (2) which is used to provide thehousing for the whole component and a cavity (3) designed within theplastic material where an optoelectronic chip (4) is mounted within.This cavity is filled with a encapsulation material (5) so that opticalradiation may be transmitted or received via this window. Electricalconnection(s) between the chip and the base material is provided by ametallic wire.

A circular groove (6) is located around the cavity. A lens structure (7)is placed on top of the base component. The lens position is preciselylocated due the groove (6) and the protruding structure on the lens (8).The encapsulation material forms a layer (9) between the lens and thebase component and provides the adhesion between the two parts. Thislayer extends out until the groove so that the adhesion is enhanced bythe larger surface area. In addition, the rough surface texture of thebase component ie. the groove (6) also promotes better adhesion.

1.-13. (canceled)
 14. A method for producing a lens structure for asurface mount optoelectronic component assembly using silicone as a basematerial, comprising the steps: fabricating a mold tool with a requiredlens profile, dispensing liquid silicone into the mold tool, heating themold tool so that the silicone is cured and hardened to form the lensstructure before being removed from the mold tool.